High temperature nickel-chromium base alloys



y 1967 s. w. KER SHAW ETAL 3,322,534

HIGH TEMPERATURE NICKEL-CHROMIUM BASE ALLOYS Filed April 30, 1965 $80 Q H 60 @J e4 8 Q 40 s 0 2 4 6 a /0 R54 CE/vf Cx/Pov/un 6 AEJVENTORSJ' 7'0 r 4472' MM y RG/Z'ZLD 714.1 P ea Amps 5y United States Patent 3,322,534 HIGH TEMPERATURE NICKEL-CHROMIUM BASE ALLOYS Stuart Walter Ker Shaw, Sutton Coldfield, and Reginald Massey Cook, Birmingham, England, assignors to The International Nickel Company, Inc., New York, N.Y., a corporation of Delaware Filed Apr. 30, 1965, Ser. No. 457,240 Claims priority, application Great Britain, Apr. 26, 1963, 16,561/ 63; Aug. 19, 1964, 33,908/64 21 Claims. (Cl. 75-171) This is a continuation-in-part of application Ser. No. 438,750, filed Mar. 10, 1965, now abandoned and Ser. No. 362,064, filed Apr. 23, 1964, now abandoned, Ser. No. 438,750 being a continuation of Ser. No. 362,064.

The present invention relates to nickel-alloys, and, more particularly, to cast nickel-base alloys suitable for use under high stress at temperatures of at least 1000 C. (1832 F.) and above as, for example, stator and rotor blades for gas turbine engines.

As is well known to those skilled in the art, demands upon research have been intensive in the endless endeavor to develop alloys capable of withstanding the ever increasing and stringent requirements imposed by commercial and industrial application. For example, the advances witnessed in the aircraft and related industries over the past two decades have been striking with regard to providing specially designed aircraft structures capa ble of operating at higher temperatures and stresses. However, it is such advances which have often been responsible for or necessitated the concomitant development of new materials which would enable the new designs to be put into use in the first instance. This aspect is typically illustrated by the aircraft gas turbine industry which has been continuously designing new stator and rotor blades for gas turbine engines, blades which are .adapted to be exposed to higher stresses and temperatures. Stator and rotor blades in cast form have received considerable attention in recent years for various reasons and there is a present need for cast alloys suitable for use in the production of such blades designed to operate ,at temperatures over 1800 F., e.g., 1900 F., and under relatively high stress. It was not too long ago that efforts were being expended to develop alloys capable of performing satisfactorily at the now comparatively low temperatures of 1200 F. or 1300 F. to 1500 F. Ina relatively short period of time the temperature demands have increased to 1800 F. and even 1900 F. and there is little reason to believe that future developments will reverse this trend.

Progress has been indeed attained in efforts to provide alloys capable of coping with temperatures of the order of 1900 F. In .an article entitled A Nickel Alloy for 1900 F. by J. C. Freche and W. 1. Waters of NASA, which article appeared in the May 1963 issue of Materials and Design, the authors, after indicating that there are commercial alloys available having good stressrupture lives at 1800 F. to 1900 F., point to a new NASA alloy having excellent stress-rupture life properties. This tantalumand vanadium-containing nickel-base NASA alloy nominally contained 8% tantalum, 6% chromium, 6% aluminum, 4% molybdenum, 4% tungsten, 2.5% vanadium, 0.125% carbon, the balance being nickel, and had a stress-rupture life of 100 hours under a stress of 15,000 p.s.i. at the high temperature of 1915 F. In this connection, it would appear that vanadium, inter alia, is an essential constituent of the NASA alloy since it improved stress-rupture life. Our experience has shown that with regard to the alloys of the present invention vanadium impairs oxidation resistance at high temperatures, e.g., 1900 F., and adversely elfects stress Patented May 30, 1967 rupture life. Good oxidation resistance becomes increasingly important the longer the period of exposure of an alloy to high temperature.

As is further known by those skilled in the art, it is often most desirable in various high temperature applications that the alloys used therefor afford good impact resistant characteristics. This desired attribute is also exhibited by certain alloys of special composition contemplated herein.

It has now been discovered that by means of a special combination of alloying constituents correlated in a controled manner, alloys are provided which exhibit a most advantageous combination of mechanical and other characteristics.

It is an object of the present invention to provide a new and improved nickel-base alloy having a novel combination of alloying constituents.

Another object of the invention is to provide a novel cast alloy suitable for use in precision cast gas turbine structures.

A further object of the invention is to provide nickelbase alloys which provide a highly satisfactory combination of stress-rupture and impact resistant properties a elevated temperature.

Other objects and advantages will become apparent from the following description taken in conjunction with the accompanying drawing in which there is depicted a curve illustrating the effect of chromium content with respect to stress-rupture life of various nickel-base alloys.

Generally speaking, the alloys of the present invention contain about 2% to about 10% chromium, from 5%, and most advantageously, from about 7%, to 19% tungsten, up to about 5% molybdenum, from 0.5% to 7% tantalum, with the sum of the contents of tungsten and tantalum being at least 7% and the sum of these two elements together with twice the content of molybdenum and two-thirds of the content of chromium being from 17.5% to 24%, from 2% to about 8% aluminum, up to about 4% titanium, up to about 0.5 carbon, e.g., 0.03% to 0.5%, up to 2.5% columbium, with the proviso that the columbium content is not greater than and advantageously is less than the tantalum content, up to 0.05% boron, up to 1.5% zirconium and the balance, apart from impurities, being nickel. The principal impurities that may be present are iron, silicon and manganese and the total amount of these elements should be as low as possible and must not exceed 3%. Preferably the iron content does not exceed 0.5 the silicon content 0.3% and the manganese content 0.3%.

The stress-rupture lives of the alloys at temperatures above 1000 C. fall as their chromium content increases above about 5%, i.e., as the chromium content of the alloys increases, their stress-rupture lives above 1000 C. increase to a maximum at a chromium content of about 5% and then falls. For the longest lives the chromium content should not exceed 9%, and most advantageously, it is from 3% to 7%.

The effect of varying the chromium content in a series of alloys of nominal composition, apart from chromium, 0.13% carbon, 2% molybdenum, 11% tungsten, 3% tantalum, 6% aluminum, 0.5 zirconium, balance nickel and impurities is illustrated by the accompanying drawing in which the stress-rupture lives under a stress of 7 t.s.i. (long tons/square inch) at 1070" C. (1958 F.) are plotted as ordinates, on a logarithmic scale, against the chromium contents of the alloys as abscissae. The drawing illustrates, as referred to above herein, that optimum stress-rupture life was achieved with chromium contents of about 5%. The resistance of the alloys to oxidation at high temperatures falls sharply when the chromium content is reduced below 2%. At higher chromium contents it increases progressively as the chromium content is increased, and the best combination of stress-rupture properties and oxidation resistance is exhibited by alloys with from to 7% chromium.

The stress-rupture lives of the alloys also depend on their aluminum content and in titanium-free alloys is greatest when the aluminum content is from 5.2% to 7.1%. When titanium is present, the value of the ex- The amount of chromium can be raised from 7% to 9% 5 pression or where maximum oxidation resistance is of impercentAl+0.7 (percent Ti) portance. is

preferably from 5.2% to 7.1%. g is zi 'i ig g; 23 68 31 5 2; 52 52 3 gg Particularly satisfactory stress-rupture properties are t h g t exhibited by alloys having compositions within the fola a f 6 mmlllm COD en 9 an Va P 10 lowing range: 0.10% to 0.16% carbon, 5.0% to 7.0% of this total at which the longest lives are obtained. With chromimum 17% to 2.3% molybdenum, 10.5% to 11.5% increasing contents of chromium this optimum value detungsten 25% to tantalum 57% to a1umi creases, and alloys contalmng 6% chromlum the num, 0.3% to 1.0% zirconium, up to 0.035% boron, with longest lives are generally obtained when the total th b l i k 1 di i i The eflect on the stress-rupture lives of varying the con- 2 (percent Mo)+percent W+Percent Ta tents of tungsten, molybdenum and tantalum in a series is f 15% to 1 19% e g 1 to 19% In of alloys all of which also contained nominally 6% chromeral, the stress-rupture lives of the alloys fall sharply as 111m, 6% alumlmlmt 013% carbon Zlfcomum, the value of the expression the balance bemg nlckel and impunties, 1s illustrated by the results 1n Table I. In this table all the alloys except 2 (percent Mo) +percentW Nos. 1, 5, 6, 7, 11, 13, 14, 15 and 17 are in accordance +percent Ta+% (percent CR) with the invention.

TABLE I Stress-rupture properties at- Alloy N0. M0, W, Ta, 2 Mo+W+Ta 9 t.s.i./1,020 C. 7 t.s.i./1,070 0.

percent percent percent +36 Gr Lite El. Life El. (hrs.) (percent) (hrs) (percent) 4 3 2 17 21 17.2 4 0 0 23 91 4.3 151 0.4 4 5 s 25 44 N.D. 70 4.0 4 5 10 27 7 ND. 4 7 0 25 31 ND. 71 3.0

7 t s.i./1,070 o 4 7 4 59 9.4 0 11 .1 28 0.8 0 11 3 74 .D. 0 11 4 45,88 N.D., 12.0 0 13 4 91 5.0 0 14 4 a2 3.3 0 15 4 59 4.9 0 14 2 78 8.6 0 14 1 as 11.4

T.s.i.=Long tons/square inch. N.D.=Not Determined.

is decreased below 17.5% or increased above 24%. When the tantalum content does not exceed about 4%, satisfactory properties are obtained with values of the above expression up to 25%.

The tantalum content of the alloys is preferably from 2% t0 6%, since poorer stress-rupture lives are obtained outside this range. The longest lives are exhibited with alloys containing not more than 5% tantalum. For the same reason the molybdenum content preferably does not exceed 3% and the tungsten content is, as noted above herein, advantageously at least 7%. When the chromium content is 5 or above, the tungsten content advantageously does not exceed 16% Table I illustrates that poorer properties are obtained when the contents of tungsten, molybdenum and tantalum are such that the value of the expression 2 (percent Mo) +percent W+percent Ta /3 (percent Cr) therefore, the columbium content does not exceed threequarters of the tantalum content and most advantageously does not exceed one-half the percentage of tantalum. This efilect is illustrated by the results in Table II, which relate to alloys of the same nominal carbon, chromium,

The stress-rupture properties of Alloy No. 3 under various conditions of stress and temperature are set forth in Table HI, 'whichalso inclules the properties of an alloy (Alloy A) of otherwise identical composition that is free from aluminum and zirconium contents as those in Table I. tantalum but contains an equiatomic amount (1.5% by TABLE II Stress-Rupture Properties 2 Mo+W+ at 7 t.s.i./l,070 0. Alloy N0. M0, Percent W, Percent Ta, Percent Cb, Percent Ta-l-3 Cr Life (hrs) El. (percent) 0 13 4 0 21 5.6 0 13 4 1 21 146, 147 6. 2, 4.8 2 11 2 o 21 74 8.6 2 11 2 1.0 21 104 6.2 2 11 3 0 22 85 N.D. 2 11 3 0.5 22 87 8.9 2 11 3 1.0 22 100 7.2 2 11 4 0 23 74 N.D. 2 11 4 0.5 23 76 4.7 2 11 4 1.0 23 82 5.1 4 7 4 0 23 59 9.4 4 7 4 0.5 23 80 8.0 4 7 4 1.0 23 85 5.3 0 11 3 0 1s 74 N.D. 0 11 3 1 18 109 16.2 0 11 3 1.5 18 78 10.1 0 11 3 2.0 18 65 6.4 0 11 3 2.5 18 29 7.6 0 11 4 0 19 75, 88 N.D., 12. 0 0 11 4 0.5 19 90 .D. 0 11 4 1.5 19 113 7.4 0 11 4 2.0 19 90 5.1 0 11 4 2.5 .19 66 8.0

In reviewing Table II it will be noted, in accordance with weight) of columbium. It will be seen that the properties the invention, stress-rupture lives as high as 100 hours or of the tantalum-containing alloy of the invention are much more under a stress of 7 t.s.i. (15,680 p.s.i.) at the exsuperior under all the test conditions employed. tremely high temperature of 1070 C. (1958 F.) can be TABLE III obtained in combination with relatively good ductility. It will be further noted that the best results were obtained Alloy No. 3 AlloyA when the columbium content did not exceed about onehalf the tantalum content. Alloy 25 had an extremely high {life El- Life El.

, t stress-rupture life of about 146 hours at the comparatively rs) (Damn (hrs) (percent) very temperautre f 10 C- A Preferred range of 5 C 75 7 g 129 28 compositions for columbium-containing alloys is as folg0tt.s .i.1/9(520; 1, 2 9.6 699 15.6 lows: 0.10% to 0.16% carbon, 5% to 7% chromium, 131 1 5 5 5 33 2:? 12.5% to 13.5% tungsten, 3.6% to 4.4% tantalum, 0.7% Hat/1,070 o.--

s5 N.D. ND.

3 t. 1,150 C 90 N.D. 44 .D. to 1.3% columblum, 5.7% to 6.8% alumlnum, 0.3% to 45 51/ N 1% zirconium, up to 0.035% boron, with the balance N D :N0t determined nickel and impurities. ELzElongation at fracture.

In further accordance with the concepts of the mvention Under a Stress f 7 m at 1100 C" Alloy 3 had a t h been sulprisillglyfound h tantalum P -Y life of 34 hours and an elongation of 14.6% at rupture. f r y from and 15 (111116 Superior to columblum 111 P The presence of cobalt in the tantalum-containing alloys viding improved stress-rupture lives at temperatures of 1000 C. and above with respect to cast alloys of the invention and with regard to other similar alloys. This is illustrated by the data shown in Table III with regard to a preferred alloy (Alloy No. 3) of the invention in com- 5 parison with a columbium containing tantalum-free alloy.

of the invention up to a total of 15% has relatively little useful efiect on their stress-rupture properties and it generally decreases stress-rupture life as is illustrated by the results set forth in Table IV which relate alloys of the 5 same nominal carbon, chromium, aluminum and zirconium contents as those in Table I.

TABLE IV Stress-rupture properties at- 2 Mo+ Alloy No. Mo, W, Ta, Ob, Co, W+ 9 t.s.i./1,020 O. 7 t.s.i./1,070 0.

percent percent percent percent percent 110 Life El. Life El.

(hrs) (percent) (hrs.) (percent) 2 11 3 0 0 85 N.D. 2 11 3 5 0 85 18. 9 2 11 3 1O 0 99 8. 2 2 11 3 15 0 9. 1 2 11 3 20 0 36 N .D. 4 7 4 0 0 59 9. 4 4 5 4 10 0 45 9. 2 4 7 4 10 0 4 7 4 10 0. 5 2 117 2 8. 7 4 7 4 10 1. 0 2 124 2 N.D. 4 7 4 10 1. 5

l =Alloy No. 44 is outside scope of invention. 1 =7 t.s.i./1,050 C.

A comparison of Alloy No. 46 with Nos. 47, 48 and 49 again illustrate the beneficial effects of columbium.

The effect of varying the aluminum content of the alloys is shown by the results in Table V for a series of alloys nominally containing, apart from the elements shown, 0.13% carbon, 6% chromium, 0.5% zirconium, balance nickel and impurities.

vanadium. This is shown by the results set forth in Table VII which sets forth the stress-rupture properties of alloys having, apart from vanadium and tantalum in the amounts indicated, the following composition: 0.13% carbon, 6% chromium, 2% molybdenum, 11% tungsten, 6% aluminum, 0.5% zirconium, nickel and impurities balance.

TABLE v Stress-rupture properties Mo., W, '1 Al, 2 Mo-l-W at 7 t.s.i./1,070 0. Alloy No. Percent Percent Percent Percent +Ta+% Cr Life (hrs.) El. (percent) The longest stress-rupture lives are obtained with alu- TABLE VII minum contents within the preferred range 5.2% to 7.1%, and alloys with aluminum contents within this range are, Stress-rupture properties attherefore, particularly sultable for gas-turbine rotor blades, which require the best poss1ble stress-rupture AHOY v, Ta, 9 psi/1,0200 C Him/170703 Q properties. At lower aluminum contents the alloys have No. percent percent higher melting points and alloys with from 5% down to Lira EL Life EL 3.5% or even 2% aluminum are suitable for parts such (his) (percent) (ms) (percent) as gas-turbine stator blades, which require a high melting point but are less highly stressed than rotor blades. W1th 4 0 5 4 145 6.2 aluminum contents above about 7% or 7.1%, lower 22:: 5 2 38 3:3 stress-rupture properties result as is illustrated by Alloy 40 No. 56 which has an aluminum content above the preferred maximum. Throughout the range of aluminum contents, from 2% to 8%, the alloys of the invention have substantially better stress-rupture properties than otherwise similar alloys in which the tantalum is wholly replaced by an equia-tomic amount of columbium.

When the alloys contain titanium, the longest stressrupture lives are obtained, other things being equal, when the value of the expression percent Al+0.7 (percent Ti) lies between 5.2% and 7.1%. This is illustrated by the results set out in the following table, which relates to alloys that nominally contained, apart from aluminum and titanium, 0.13% carbon, 6% chromium, 2% molybdenum, 11% tungsten, 3% tantalum, 0.5% zirconium, balance nickel and impurities.

As referred to above herein, vanadium impairs the resistance of the alloys to oxidation at high temperatures, and from this point of view is undesirable. Further, with alloys in accordance with the invention the stress-rupture properties are also impaired even by small additions of To insure satisfactory stress-rupture properties, the carbon content is at least 0.03% and is preferably at least 0.05% but variation of the carbon content of the alloys within the range 0.05 to 0.3% has little effect on their stress-rupture properties. However, in achieving a high level of resistance to impact, it is most important that the carbon content be less than 0.03%, e.g., 0.001% to 0.0275 In this connection, the carbon content is preferably as low as possible, e.g., less than 0.02% or even less than 0.01%, though a trace of carbon will almost inevitably be present.

With carbon contents below 0.03%, stress-rupture properties are not as high as would otherwise be the case; however, this property loss can be greatly minimized with alloys which advantageously contain both zirconium and boron. Zirconium and 'boron improve the stress-rupture lives of the alloys, which, regardless of carbon content, preferably contain at least 0.05 e.g., at least 0.1%, up to 1% zirconium, with or without boron in such an amount that the value of the expression: percent Zr-l- 10X (percent B) is preferably from 0.2% to 1.2%. While it is not absolutely essential (although much pre ferred) that the alloys contain boron when the carbon content is above 0.03%, at least 0.01% boron should be present with lower carbon contents in order to achieve a good combination of stress-rupture life and resistance to impact. Further in this regard, it is preferred that the boron content not exceed 0.035% when the alloys contain more than 0.03% carbon. The effect of zirconium and boron on alloys containing more than 0.03% carbon is illustrated in Table VIII, the alloys containing, apart from zirconium and boron in the amounts indicated, 0.13% carbon, 6% chromium, 2% molybdenum, 11% tungsten, 3% tantalum, 6% aluminum, balance nickel and impurities.

TABLE VIII Stress-rupture properties at Alloy No. Zr, 13, 5 t.s.i./1,050 C. 6 t.s.i./l,050 C. 9 t.s.i./1,050 0.

percent percent Life E1. Life El. Life E1.

(hrs) (percent) (hrs.) (percent) (hrs) (percent) Alloy No. 68 had the poorest stress-rupture life and it will be noted that this alloy having a boron content of 0.1% is outside the present invention.

Impact resistance characteristics obtainable with low carbon contents are illustrated in Table IX, All-0y No. 3 being used as a basis of comparison with the alloys identified as Nos. 69, 70 and 71 which are of the same nominal composition as Alloy No. 3 except for the indicated amounts of carbon, zirconium and boron.

Comparison of Alloy No. 3 with Alloys Nos. 69, 70 and 71 shows the striking improvement in impact resistance attributable to low carbon contents. The drastic fall in stress-rupture life that resulted from lowering the carbon content (in the absence of boron) is greatly affected by the presence of boron. This is shown by the test results for the boron-containing Alloys Nos. 70 and 71 according to the invention.

The results in Table IXa further illustrate the effects of varying the boron content in a series of low-carbon alloys each containing 0.004% carbon, 0.25% zirconium and otherwise having the same base composition as those in Table IX.

TABLE IXa Stress-rupture properties Impact at 15 t.s.i./950 0. value at Alloy No. B, percent 850 C. (it-lb.) Life (hrs.) El. (percent) It will be :seen that when the carbon content is reduced below 0.03% a high level of properties is obtained at boron contents as high as 0.075 or 0.08%.

Table X contains some examples of low-chromium alloys and shows that their properties are good as long as the value of the expression 2(percent Mo) +percent W-l-percent Ta+ /3 (percent Cr) lies between 17.5% and 24%, and the tungsten content does not exceed 19%.

All the alloys nominally contained, in addition to the elements mentioned, 0.13% carbon, 6% aluminium, 3% chromium, 10% cobalt, 0.5% zirconium, balance nickel and impurities.

TABLE X Stress-rupture properties W, Ta, Ch, 2 Mo+W+Ta+ at 7 t.s.i./l,100 0. Alloy No. percent percent percent Cr Life (hrs) El. (percent) 16 3 2 21 48 12. 6 16 4 0 22 58 N.D. 16 4 1 22 56 8. 6 l6 4 2 22 42 18 1 0 22 48 N.D. 18 1 1 21 54 N.D. 18 4 0 24 56 N.D. 1 0 23 0.2 19. 6 20 2 0 24 1. 4 10.6 20 3 0 4.9 4. 3 20 4 0 26 7 8. 5

1 Alloys Nos. 86, 87, 88 and 89 are outside the scope of the invention.

The alloys may be air melted, but are preferably melted under vacuum. This is particularly apropos in obtaining alloys with low carbon contents. Under such conditions, carbon reacts with oxides introduced by the charge materials and is substantially eliminated as carbon monoxide. Whether or not they are vacuum-melted, the alloys are advantageously subjected to a vacuum-refining treatment comprising holding them in the molten state under high vacuum before casting the melt. We prefer to hold the melt at a temperature of 1400 C. to 1600 C. at not more than 100 microns pressure for a period of at least 15 minutes and advantageously for 60 minutes or more. The duration of the treatment depends to some extent on the purity of the ingredients of the melt, a longer time being required when less pure ingredients are employed.

When making small castings, for example, turbine blades or stress-ru ture testpieces, the alloys are preferably cast under vacuum, but when making large castings from a melt that has been produced or refined under vacuum, it makes little difference to the properties obtained whether casting is carried out in vacuum, inert gas or air. All the stress-rupture test results given in this specification were obtained in testpieces machined from cast specimens that had been vacuum-cast from vacuum-melted material that had been vacuum-refined for at least 15 minutes at 1500 C. under a pressure of less than 1 micron.

Articles and parts cast from the alloys may be used in the as-cast condition for high temperature service, for example, as rotor blades in gas turbine engines. If desired, the alloys may be homogenized by heating in the temperature range 850 C. to 1250 C. before being put into service.

For use at temperatures above 1000 C. under conditions such as are encountered in gas turbine engines, involving both oxidation and sulfur attack, articles and parts made from the alloys are preferably provided with a protective coating, for example, of aluminum.

Although the present invention has been described in conjunction with preferred embodiments, it is to be understood that modifications and variations may be resorted to without departing from the spirit and scope of the invention, as those skilled in the art will readily understand. Such modifications and variations are considered to be within the purview and scope of the invention and appended claims.

We claim:

1. A nickel-base alloy characterized by good stressrupture properties at temperatures of 1800 F. and above, said alloy consisting essentially, in weight percent, of about to about 7% chromium, about 10.5% to 11.5% tungsten, about 1.7% to 2.3% molybdenum, about 2.6% to 3.4% tantalum, about 5.7% to 6.8% aluminum, about 0.1% to 0.16% carbon, up to 0.035% boron, about 0.03% to 1% zirconium and the balance nickel.

2. A nickel-base alloy characterized by good stressrupture properties at temperatures of 1800 F. and above, said alloy consisting essentially, in weight ercent, of about 5% to 7% chromium, about 12.5% to 13.5% tungsten, about 3.6% to 4.4% tantalum, about 0.7% to 1.3% columbium, about 5.7% to 6.8% aluminum, about 0.1% to 0.16% carbon, up to about 0.035% boron, about 0.03% to 1% zirconium and the balance essentially nickel.

3. A nickel-base alloy characterized by a combination of good stress-rupture life and resistance to impact at high temperatures, said alloy consisting essentially, in weight percent, of about 2% to about chromium, from 5% to 19% tungsten, up to 5% molybdenum, from 0.5% to 7% tantalum with the sum of the contents of tungsten and tantalum being at least 7% and the sum of these two elements plus twice the percentage of molybdenum plus two-thirds the percentage of chromium being from 17.5% to 24%, from 2% to 8% aluminum,

up to about 4% titanium, up to less than 0.03% carbon, up to 2.5% columbium with the proviso that the columbium content is not greater than the tantalum content, up to 15% cobal, about 0.01% to 0.08% boron, about 0.05% to 1.5% zirconium and the balance essentially nickel.

4. The alloy as set forth in claim 3 wherein the carbon content does not exceed 0.02%.

5. An alloy according to claim 3 containing 5% to 9% chromium, 7% to 16% tungsten, up to 5% molybdenum, 0.5% to 7% tantalum, 2% to 8% aluminum, up to 4% titanium, up to 2.5% columbium, 0.001% to 0.0275% carbon, about 0.01% to 0.05% boron, about 0.1% to 1% zirconium, and the balance nickel.

6. An alloy according to claim 3 containing 2% to 5% chromium.

7. An alloy in accordance with claim 3 containing 7% to 16% tungsten, up to 3% molybdenum, 2% to 6% tantalum, 5.2% to 7.1% aluminum with the aluminum and any copresent titanium being correlated such that the percentage of aluminum plus 0.7 times the percentage of titanium equals 5.2% to 7.1%, 0.001% to 0.0275% carbon, 0.01% to 0.05% boron and 0.1% to 1% zircomum.

8. A nickel-base alloy characterized by good stressrupture properties at temperatures of 1800 F. and above, said alloy consisting essentially, in weight percent, of about 2% to about 10% chromium, from 5% to 19% tungsten, up to 5% molybdenum, from 0.5% to 7% tantalum with the sum of the contens of tungsten and tantalum being at least 7% and the sum of these two elements plus twice the percentage of molybdenum plus two-thirds the percentage of chromium being from 17.5 to 24%, from 2% to 8% aluminum, up to about 4% titanium, up to about 0.5% carbon, up to 2.5% columbium with the proviso that the columbium content is not greater than the tantalum content, up to 0.05% boron, up to about 1.5% zirconium, up to a total of 3% of iron, manganese and silicon, and the balance nickel.

9. A nickel-base alloy characterized by good stressrupture properties at temperatures of 1800 F. and above, said alloy consisting essentially, in weight percent, of about 2% to about 5% chromium, from 5% to 19% tungsten, up to 5% molybdenum, from 0.5% to 7% tantalum with the sum of the contents of tungsten and tantalum being at least 7% and the sum of these two elements plus twice the percentage of molybdenum plus two-thirds the percentage of chromium being from 17.5 to 24%, from 2% to 8% aluminum, up to about 4% titanium, up to about 0.5% carbon, up to 2.5% columbium with the proviso that the columbium content is not greater than the tantalum content, up to 0.05% boron, up to about 1.5% zirconium, up to 15% cobalt, up to a total of 3% of iron, manganese and silicon, and the balance nickel.

10. An alloy in accordance with claim 9 containing 7% to 16% tungsten, 2% to 6% tantalum, 5.2% to 7.1% aluminum with the aluminum and any copresent titanium being correlated such that the percentage of aluminum plus 0.7 times the percentage of titanium equals 5.2% to 7.1%, up to 0.3% carbon, up to 0.035% boron and 0.1% to 1% zirconium.

11. An alloy in accordance with claim 8 and containing zirconium in an amount of about 0.05% to 1%.

12. An alloy in accordance with claim 8 in which the tungsten is from 7% to 16%.

13. An alloy in accordance with claim 12 in which the chromium is from 5% to 9%.

14. An alloy in accordance with claim 8 containing 7% to 16% tungsten, 2% to 6% tantalum, 5.2% to 7.1% aluminum with the aluminum and any copresent titanium being correlated such that the percentage of aluminum plus 0.7 times the percentage of titanium equals 5.2% to 7.1%, up to 0.3% carbon, up to 0.035% boron and 0.1% to 1% zirconium.

15. An alloy in accordance with claim 8 and containing 3% to 7% chromium, from 7% to 19% tungsten, up to 3% molybdenum, 2% to 6% tantalum, about 2% to about 8% aluminum, 0.05% to 0.3% carbon, up to 0.035% boron and up to 1% zirconium.

16. An alloy in accordance with claim 15 wherein the chromium and tungsten contents are further correlated such that when the chromium exceeds the tungsten does not exceed 16%.

17. An alloy in accordance with claim 16 wherein zirconium is present in an amount of at least 0.1%.

18. An alloy in accordance with claim 17 wherein boron is present from about 0.01% to about 0.035%.

19. An alloy in accordance with claim 8 and containing 3% to 7% chromium, 7% to 16% tungsten, up to 3% molybdenum, 2% to 6% tantalum, 5.2% to 7.1% aluminum with the, aluminum and any copresent titanium being correlated such that the percentage of aluminum plus 0.7 times the percentage of titanium equals 5.2% to 7.1%, 0.05% to 0.3% carbon, a small but elfective amount of columbium up to 2.5% to enhance the stress- 14 rupture life of the alloy, the columbium not exceeding one-half the percentage of tantalum, 0.01% to 0.035% boron and 0.1% to 1% zirconium.

20. An alloy in accordance with claim 19 wherein the zirconium is correlated with the boron such that the percentage of zirconium plus ten times the percentage of boron is from 0.2% to 1.2%.

21. A cast alloy having a composition as set forth in claim 8.

References Cited UNITED STATES PATENTS 2,948,606 8/1960 Thielemann --171 2,994,605 8/ 1961 Gill et al. 75-171 3,026,198 3/1962 Thielemann 75171 3,085,005 4/1963 Michael et al. 75-171 3,164,465 1/ 1965 Thielemann 75-171 DAVID L. RECK, Primary Examiner. R. O. DEAN, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,322, 534 May 30, 1967 Stuart Walter Ker Shaw et al.

It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 1, line 16, for "nickel-alloys" read H nickelbase alloys line 54, for "1900 F." read 1900F column 3, line 22, for "(percent CR)" read (percent Cr) column 4, line 11, for "chromimum" read chromium column 6, line 3, for "inclules" read includes columns 5 and 6, TABLE IV, heading to the fifth column, for "Cb, percent" read Co, percent same TABLE, heading to the sixth column, for "Co, percent" read Cb, percent column 11, line 24, for "in" read on column 12, line 4, for "cobal" read cobalt line 30, for "contens" read contents Signed and sealed this 28th day of November 1967.

(SEAL) Attest:

EDWARD M. FLETCHER,JR. EDWARD J. BRENNER Attesting Officer Commissioner of Patents 

8. A NICKEL-BASE ALLOY CHARACTERIZED BY GOOD STRESSRUPTURE PROPERTIES AT TEMPERATURES OF 1800*F. AND ABOVE, SAID ALLOY CONSISTING ESSENTIALLY, IN WEIGHT PERCENT, OF ABOUT 2% TO ABOUT 10% CHROMIUM, FROM 5% TO 19% TUNGSTEN, UP TO 5% MOLYBDENUM, FROM 0.5% TO 7% TANTALUM WITH THE SUM OF THE CONTENS OF TUNGSTEN AND TANTALUM BEING AT LEAST 7% AND THE SUM OF THESE TWO ELEMENTS PLUS TWICE THE PERCENTAGE OF MOLYBDENDUM PLUS TWO-THIRDS THE PERCENTAGE OF CHROMIUM BEING FROM 17.5% TO 24%, FROM 2% TO 8% ALUMINUM, UP TO ABOUT 4% TITANIUM, UP TO ABOUT 0.5% CARBON, UP TO 2.5% COLUMBIUM WITH THE PROVISO THAT THE COLUMBIUM CONTENT IS NOT GREATER THAN THE TANTALUM CONTENT, UP TO 0.05% BORON, UP TO ABOUT 1.5% ZIRCONIUM, UP TO A TOTAL OF 3% OF IRON, MANGANESE AND SILICON, AND THE BALANCE NICKEL. 